The northern lights have long captivated observers on the ground, but the company now says it is looking for a European base to launch trips that will go high enough to delve inside the glowing sky for the first time. "No human being has ever flown into an aurora borealis," said Will Whitehorn, president of Virgin Galactic. "You have to go beyond the edge of space. I think that will be a magical and mystical experience."

Sir Richard's venture is a collaboration with Burt Rutan, who designed SpaceShipOne, the craft that won the $10m (£5.2m) Ansari X-prize in 2004. The prize was awarded for flying a spacecraft capable of carrying three people to the edge of space twice in two weeks. Mr Rutan's company, Scaled Composites, in Mojave, California, is working on a successor called SpaceShipTwo, which will carry six passengers and two pilots.

Virgin Galactic will not be drawn on exactly when the tourist flights will start but most observers expect them to launch in 2008 or 2009. The company already has 100 "founder" members who have each paid $200,000 for a ticket on one of the early flights. Once testing of SpaceShipTwo is completed, the first flight will carry Virgin Galactic staff and the second will take Sir Richard himself.

The company is based in New Mexico where the state government is building a spaceport, but a launch site for aurora flights in Europe is yet to be decided. "It's very, very difficult to find locations in Europe," Mr Whitehorn told a conference on space tourism at the Royal Aeronautical Society in London on Wednesday. Most suitable airports were too close to population centres, and only 55 airports in the world had runways long enough.

The most likely location for European flights is Kiruna in far north Sweden. Mattias Abrahamsson, business development manager at the Swedish Space Corporation, said the "spectacular display" was visible from Kiruna between August and April. "It looks like a curtain of light that moves over the sky," he said. But the view should be much clearer from SpaceShipTwo at around 75 miles up.

The lights are caused by charged particles in the solar wind interacting with the atmosphere. The Earth's magnetic field protects us from most of these, but they are able to get through at the poles.